Sole for a trail running shoe

ABSTRACT

The present invention relates to a sole for a shoe, in particular a trail running shoe. The sole includes at least one first ground engaging profile element having a first flexibility and at least one second ground engaging profile element having a second flexibility. The second profile element has a ridge or riblike shape and the second flexibility is greater than the first flexibility. The invention also relates to a sole for a shoe including at least two ground engaging profile elements and a plurality of second ground engaging profile elements. The invention further relates to a shoe including a sole having at least one first ground engaging profile element with a first flexibility and at least one second ground engaging profile element with a second flexibility.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application incorporates by reference, and claims priorityto and the benefit of, German patent application serial number19957821.4, which was filed on Dec. 1, 1999.

TECHNICAL FIELD

[0002] The invention generally relates to articles of footwear, such assports shoes, and in particular to a sole for a trail running shoe.

BACKGROUND INFORMATION

[0003] When shoes, in particular running shoes, are constructed, thedesign of the sole is of particular importance. The sole performsseveral functions. The sole should, depending on the intended use of theshoe, provide sufficient cushioning to reduce stresses arising on thehuman body. Further, the design of the lower part of the sole, theoutsole, determines the interaction of the shoe with the ground. Theoutsole can be designed to optimize the grip of the shoe on the ground.

[0004] The optimal design of a sole for a running shoe, for example thenumber, distribution, shape, and flexibility of profile elementsarranged thereon, strongly depends on the intended use of the shoe. Theterm running shoe may include all kinds of shoes where the sole directlycontacts the ground, for example jogging shoes, sprint shoes, or hikingboots. It is, for example, desirable that a sole for a hiking boot to beused on rough ground preferably has a coarser profile structure than ashoe for indoor sports.

[0005] It is, however, often a problem with sports shoes that the exactfield of use of the shoe, i.e., the ground on which the shoe is to beused, is not clearly determined in advance. For example, running shoesfor trail running are often used on a variety of different surfaces. Intrail running, the athlete runs over long distances not only on evenasphalt roads, but also on gravel roads or woodland trails. Furthermore,depending on weather conditions, the ground may be either dry and hardor wet and muddy. Therefore, it is desirable for a manufacturer of suchshoes to construct soles that provide sufficient grip on a plurality ofground surfaces, thereby allowing the multipurpose use of a trailrunning shoe.

[0006] It is known in the prior art to use soles with differentcharacteristics. See, for example U.S. Pat. No. 5,634,283, U.S. Pat. No.4,271,608, U.S. Pat. No. 4,398,357, and U.S. Pat. No. 5,926,974, thedisclosures of which are hereby incorporated by reference in theirentirety.

[0007] Up till now, different sole materials were almost exclusivelyemployed with respect to the use on grounds with different hardnesses.Other objectives included the self-cleaning of the profile and thereduction in the overall weight of the shoe. The problem of using aparticular shoe on ground surfaces with different roughnesses, e.g.,asphalt or gravel, has until now not been addressed.

[0008] It is, therefore, an object of the present invention to provide asole for a shoe, in particular a trail running shoe, that assures areliable grip on ground surfaces of different roughnesses.

SUMMARY OF THE INVENTION

[0009] In one aspect, the invention relates to a sole for an article offootwear. The sole includes at least one first ground engaging profileelement with a first flexibility and at least one second ground engagingprofile element with a second flexibility. The second profile elementhas a ridge or riblike shape and the second flexibility is greater thanthe first flexibility.

[0010] In another aspect, the sole includes at least two first groundengaging profile elements with a first flexibility and a plurality ofsecond ground engaging profile elements with a second flexibility. Theplurality of second profile elements are arranged on the sole toencompass the at least two first profile elements. The secondflexibility is greater than the first flexibility.

[0011] In yet another aspect, the invention relates to an article offootwear. The article of footwear includes a sole having at least onefirst ground engaging profile element with a first flexibility and atleast one second ground engaging profile element with a secondflexibility. The second profile element has a ridge or riblike shape andthe second flexibility is greater than the first flexibility.

[0012] In some embodiments, the first and the second profile elementsare substantially the same height. In other embodiments, the first andthe second profile elements are about 1 mm to about 10 mm high,preferably about 3 mm to about 8 mm high, and more preferably about 5 mmhigh. In still other embodiments, the height of the first profileelement at least slightly exceeds the height of the second profileelement. Both profile elements may simultaneously contact on even groundsurfaces when the first profile element is compressed by the weight of awearer.

[0013] In some further embodiments, a plurality of first profileelements are arranged in a forefoot area and a midfoot area of the sole.These areas of the sole may be more critical to gripping during push-offfrom the ground. Additional first profile elements can be arranged alongan outer edge of the forefoot area and the midfoot area of the sole.This arrangement may improve sideways grip. In other embodiments, thefirst profile elements are essentially arcuate or sickle-shaped and/orcan be oriented substantially perpendicular to a longitudinal axis ofthe sole. The substantially perpendicular orientation may aid push-offin a forward direction.

[0014] In still some further embodiments, the second profile elementsinclude parallel ridges spaced apart from each other to allowsubstantially independent deflection of each of the ridges. In variousembodiments, the ridges are about 0.5 mm to about 3.0 mm wide andpreferably about 1.0 mm to about 2.0 mm wide. The parallel ridges arespaced about 0.5 mm to about 4.0 mm apart and preferably about 1.0 mm toabout 2.0 mm apart. This spacing allows the ridges to deflect on roughsurfaces independently of each other. In other embodiments, a pluralityof second profile elements can be arranged around the at least one firstprofile element, thereby obtaining an isolated first profile elementwhen the second profile elements are deflected. Such an arrangement iswell suited for engaging a rough surface. In still other embodiments,the at least one second profile element can be oriented substantiallyperpendicular to a longitudinal axis of the sole.

[0015] In some additional embodiments, the sole includes an elongateindentation disposed between a forefoot part and a midfoot part andextending from a lateral side to a medial side of the sole to facilitategreater flexibility in a wearer's natural gait cycle. In otherembodiments, the sole may include a reinforcing element disposed in themidfoot area of the sole for support of an arch of a wearer's footand/or a damping element disposed in a heel area of the sole.

[0016] These and other objects, along with advantages and features ofthe present invention herein disclosed, will become apparent throughreference to the following description of embodiments of the invention,the accompanying drawings, and the claims. Furthermore, it is to beunderstood that the features of the various embodiments described hereinare not mutually exclusive and can exist in various combinations andpermutations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the drawings, like reference characters generally refer to thesame parts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings in which:

[0018]FIG. 1 is a planar schematic view of an outsole of one embodimentof an article of footwear according to the invention; and

[0019]FIG. 2 is a perspective schematic view of the embodiment of FIG.1.

DETAILED DESCRIPTION

[0020] One embodiment of the present invention includes a sole 1 withessentially two groups of downwardly extending profile elements. For thesake of simplicity, only generally commonly configured profile elements10, 20 of the two groups are identified in FIGS. 1 and 2. It is,however, to be understood that the following description relates to allprofile elements of each respective group, where variations within oneor the other group concerning the size and the orientation are possible.Further, the sole depicted in FIGS. 1 and 2 is for a left shoe; however,it is to be understood the right shoe is typically a mirror image of theleft shoe and the description applies to both the left and right shoes.

[0021] As can be seen from FIG. 1, which presents a view from the bottomof a shoe 2, nine first profile elements 10 are arranged on the medialand lateral midfoot part 6, 7 and the lateral forefoot part 8 of thesole 1. The first profile elements 10 may be embedded into a pluralityof ridge or riblike second profile elements 20. This arrangement of theelements 10, 20 corresponds to the parts of the sole 1 that areimportant for a good grip, in particular during the rolling-off andpushing-off phase of a step cycle. For additional grip during groundcontact with the heel, additional profile elements (not shown) can bearranged in the heel part of the sole.

[0022] The first profile elements 10 are, in their originalconfiguration, about 0.5 mm higher than the second profile elements 20,so that under compression by the weight of an athlete, both groups ofprofile elements contact the ground. As a result, a comparatively denseground contacting profile results, as can be seen in FIG. 2, therebyproviding good grip on an even ground surface, such as an asphalt roador a gymnasium floor. In the embodiment shown in FIGS. 1 and 2, theheight of the profile elements 10, 20 is about 5 mm; however, otherheight dimensions, for example between about 1.0 mm and about 10.0 mm,are also possible.

[0023] The first profile elements 10 may be made of a comparatively hardand relatively inflexible material. They deform only slightly understress during ground contact and are, therefore, able to penetrate theground on which a sole 1 according to the invention is used. In someembodiments, the first profile elements 10 have a Shore hardness ofapproximately 65A.

[0024] In contrast thereto, the second profile elements 20 may be madeout of a soft and sticky rubber, thereby providing a greater flexibilitythan the first profile elements and a good grip even on wet surfaces duealso, in part, to their thin, riblike configuration. In someembodiments, the second profile elements 20 have a Shore hardness ofapproximately 60A. Due to their greater flexibility, the second profileelements 20 are forwardly or backwardly deflected by protrusions of theground (see arrow 21 in FIG. 2). As a result, they retract with respectto the first profile elements 10 and no longer extend as far downwardfrom the sole 1 as the first profile elements 10. This occurs most oftenduring running on ground surfaces with great roughness, for examplegravel roads. The deflection of the second profile elements 20 resultsin an overall profile of the sole dominated by the harder first profileelements 10 such that a comparatively rough sole 1 resembling a spikedsole is obtained. In this situation, the first profile element 10 isable to penetrate the ground or to engage the protrusions of the groundand the grip of the sole 1 under these ground conditions is improved.Because of the greater flexibility of the second profile elements 20,the second profile elements 20 together with the first profile element10 adapt to the irregularities of the ground surface. In the situationwhere the sole is used on a comparatively even surface, for exampleasphalt or the surface of a gymnasium floor, the first and secondprofile elements 10, 20 together provide the contact area of the sole 1necessary for a good grip.

[0025] The second profile elements 20, which can also be described aslamella-like structures, are shown in FIGS. 1 and 2 with parallel ribsoriented generally perpendicularly to a longitudinal axis 5 of the sole1; however, other shapes and arrangements of the second profile elements20 are possible. For example, the second profile elements 20 could beconcentric rings disposed around the first profile elements 10 or couldbe irregularly arranged longitudinal units with an arbitraryorientation.

[0026] In the embodiment shown in FIGS. 1 and 2, the second profileelements 20 have a width of about 1.0 mm to about 2.0 mm and are spacedabout 1.0 mm to about 2.0 mm apart. These values, however, are onlyapproximate values. In practice, the spacing of the second profileelements 20 with respect to each other is determined by the requirementthat they do not interfere with each other when they deflect, otherwisethey may lose their greater flexibility with respect to the firstprofile elements 10.

[0027] In the embodiment shown in FIGS. 1 and 2, the first profileelements 10 have an essentially sickle-shaped design and are oriented,as are the second profile elements 20, essentially perpendicularly tothe longitudinal axis 5 of the sole 1. Such an arrangement supports, inparticular, a forwardly directed push-off of a wearer of the shoe 2.Other possible shapes and orientations of the first profile elements 10are possible, for example a Z-like shape and/or an orientation parallelto or at an acute angle to the longitudinal axis 5 of the sole 1.

[0028] Further details of a sole 1 according to the invention are shownin FIGS. 1 and 2. To support not only a forwardly directed push-off, butalso the sideways grip of the shoe 2, additional first profile elements11 may be arranged along the medial and lateral edges of one or more ofthe midfoot part 6, 7 and forefoot part 8, 9, where their orientationfollows essentially the course of the edge of the sole 1. One or moreseparate profile elements 12 are arranged perpendicularly to thelongitudinal axis 5 of the sole 1 in the medial forefoot part 9, whichprovides good grip in the last phase of the step cycle.

[0029] Additionally, the medial and center part of the forefoot can beprovided as a stable rolling-off surface 31 extending upwardly from thesole 1 over the front part of the upper 3 of the shoe 2, therebyincreasing the life of the shoe 2. In the embodiment shown in FIG. 2,the rolling-off surface 31 is ribbed with relatively thick ridges;however, other profile shapes are possible.

[0030] Between the forefoot part 8, 9 and the midfoot part 6, 7 of thesole 1 and extending from the medial to the lateral side is a continuousgroove-like indentation 40. This indentation 40 allows the bendingstiffness of the sole to be selectively reduced in this region in orderto reduce impairment of the natural rolling-off movement of the footwith the toes.

[0031] Additional ribs 50 may be provided in the rear area of themidfoot part 6, 7 close to the arrangement of the first and secondprofile elements 10, 20. The additional ribs 50 may have amirror-inverted orientation and arcuate shape with respect to the firstprofile elements 10. Thus, forward sliding is effectively avoided duringthe landing phase of a step cycle when the foot contacts the ground.Whereas the profile elements 10, 20 primarily support the forwardlydirected push-off, the additional ribs 50 serve to decelerate the shoeduring landing on the ground. In some embodiments, the additional ribs50 have metal surfaces to improve their grip on soft ground.

[0032] A reinforcing element 60 may be disposed between the midfoot part6, 7 and the heel part 15. The element 60 supports the arch of the footand may increase stability of the shoe 2. Whereas the parts of the sole1 described until now are made out of more or less flexible materialsand serve for improving the grip of the shoe, the reinforcing element 60is preferably a rigid structural element of the sole 1 and is preferablymade out of a stable plastic material. The reinforcing element 60 isdisposed on the medial side of the sole 1 and has a three-dimensionalshape. In the embodiment shown in FIG. 2, the reinforcing element 60extends into the midfoot and heel parts 6, 7, 15; however, the degree ofthe extension may vary. It is also possible that the reinforcing element60 extends over the complete width of the sole 1 to the lateral side.

[0033] The heel part 15 of the sole 1 may include on its lateral side 16a damping element 70. This may be desirable, because most athletes firstcontact the ground with this part of the sole, which typically is wherethe greatest stress arises. It is, however, also possible that thedamping element 70 extends over the complete heel part 15 or just themedial side 17 of the heel part 15. The surface of the damping elementmay include a combination of first and second profile elements 10, 20according to the invention. For the sake of simplicity, the embodimentshown in FIG. 2 has a simple grooved profile. In some other embodiments,additional ribs 80 may be arranged on the medial side of the heel part,which by their inclined orientation help avoid sideways sliding of theshoe immediately after the first ground contact.

[0034] Having described certain embodiments of the invention, it will beapparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the invention. The describedembodiments are to be considered in all respects as only illustrativeand not restrictive. Therefore, it is intended that the scope of thepresent invention be only limited by the following claims.

What is claimed is:
 1. A sole for an article of footwear, the solecomprising: at least one first ground engaging profile element with afirst flexibility; and at least one second ground engaging profileelement with a second flexibility, wherein the second profile elementhas a riblike shape and the second flexibility is greater than the firstflexibility.
 2. A sole according to claim 1, wherein the first and thesecond profile elements are substantially the same height.
 3. A soleaccording to claim 1 or 2, wherein a plurality of second profileelements are arranged around the at least one first profile element. 4.A sole according to claim 3, wherein the plurality of second profileelements comprise parallel ridges spaced apart from each other to allowsubstantially independent deflecting of the ridges.
 5. A sole accordingto claim 4, wherein the ridges are about 1 mm to about 2 mm wide.
 6. Asole according to claim 4, wherein the ridges are spaced about 1 mm toabout 2 mm apart.
 7. A sole according to claim 1, wherein the at leastone second profile element is oriented substantially perpendicular to alongitudinal axis of the sole.
 8. A sole according to claim 1, wherein aplurality of first profile elements are arranged in a forefoot area anda midfoot area of the sole.
 9. A sole according to claim 8, wherein theplurality of first profile elements are essentially sickle-shaped.
 10. Asole according to claim 1, wherein the at least one first profileelement is oriented substantially perpendicular to a longitudinal axisof the sole.
 11. A sole according to claim 10, wherein additional firstprofile elements are arranged along an outer edge of a forefoot area anda midfoot area of the sole.
 12. A sole according to claim 1, wherein thefirst and the second profile elements are between about 1 mm to about 10mm high.
 13. A sole according to claim 1, wherein the first and thesecond profile elements are about 5 mm high.
 14. A sole according toclaim 1, further comprising an elongate indentation disposed between aforefoot part and a midfoot part extending from a lateral side to amedial side of the sole to facilitate flexibility in the sole in awearer's natural gait cycle.
 15. A sole according to claim 1, furthercomprising a reinforcing element disposed in a midfoot area of the solefor support of an arch of a wearer's foot.
 16. A sole according to claim1, further comprising a damping element disposed in a heel area of thesole.
 17. A sole for an article of footwear, comprising: at least twofirst ground engaging profile elements with a first flexibility; and aplurality of second ground engaging profile elements with a secondflexibility, wherein the plurality of second profile elements arearranged on the sole to encompass the at least two first profileelements and the second flexibility is greater than the firstflexibility.
 18. An article of footwear including a sole, the solecomprising: at least one first ground engaging profile element with afirst flexibility; and at least one second ground engaging profileelement with a second flexibility, wherein the second profile elementhas a riblike shape and the second flexibility is greater than the firstflexibility.